In order to solve the problem of poor heat dissipation existed in the conventional LED module, the means of FR-4 printing plate, metal core PCB (MCPCB), and ceramic PCB are used to radiate heat. In which, the thermal conductivity of FR-4 is smaller than 1 W/m*K, the thermal conductivity of MCPCB is about 2 to 3 W/m*K, on the other hand, the thermal conductivity of aluminum oxide ceramic is 25 W/m*K. It can be seen that the ceramic PCB has a relatively high thermal conductivity, thus, the technologies, such as ceramic mixing circuit (HIC), low temperature co-fired ceramic (LTCC), high temperature co-fired ceramic (HTCC), direct bonding copper (DBC), and direct plating copper method (DPC), are wildly used for manufacturing of the LED module.
The circuit is usually formed on the surface of the ceramic substrate with a thinner thickness, so that the heat generated by the LED can be rapidly and efficiently transferred from the LED to the heat sink via the ceramic substrate. However, the ceramic substrate with the thinner thickness is easily broken in practice due to the poor mechanical strength thereof.